“Yeah, but I heard you only had a few soldiers in Chalphy. And I know you, Sigurd. You are always jumping into this kind of stuff without thinking. Especially with Father being away... I knew I had to come.”
—Ethlyn, to Sigurd in Genealogy of the Holy War

Ethlyn (エスリン Esurin, translated Ethlin in the Fire Emblem Museum and Eslin in the Super Tactics Book) is a playable character from Fire Emblem: Genealogy of the Holy War. She is Sigurd's younger sister, the wife of Prince Quan of Leonster, the mother of Altena and Leif, and the aunt of Seliph. Despite being the younger sibling, Ethlyn became Sigurd's parent figure after the death of their mother. She is said to be greatly admired by Finn's compatriot Selfina, who looked up to her motherly, elegant and kind character.

Ethlyn is killed alongside Quan while protecting her daughter Altena during Travant's ambush during the Yied Massacre in Chapter 5. Quan is killed shortly afterwards, with Travant subsequently kidnapping Altena.

According to unofficial manga-based statistics, Ethlyn was born in Gran 739. She stands at 164 centimeters in height, weighs 47.1 kilograms, and her blood type is A.

As a mounted unit, Ethlyn has much greater movement than Adean and can heal just as well. She can also be used as a combat unit. After obtaining the Light Sword from Deirdre in Chapter 2, Ethlyn can attack or defend from a distance with the sword's magic. Adean will also give Ethlyn a Return Staff in Chapter 1 when they speak. The player should have Ethlyn sell her staves before the end of Chapter 3, as her son, Leif, will not inherit them.